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Java Simplified. Extensions and Useful Constructs for the Java Platform. Codeprimate Elements (a.k.a. cp-elements) is a Java library and micro-framework used to simplify the development of software applications written in Java. Elements packages several APIs into one library in order to address various application concerns and aspects of software design and development collectively and conveniently. Elements is a highly simple, yet robust and proven library built on solid OO principles, software design patterns and best practices to effectively solve common and reoccurring problems in software development. Write better Java!

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/*
 * Copyright 2011-Present Author or Authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.cp.elements.lang;

import java.util.concurrent.Callable;

/**
 * Interface defining a contract for {@link Object Objects} that can be executed.
 * 
 * This {@link Class interface} is similar in purpose and function to the {@link java.lang.Runnable}
 * and {@link java.util.concurrent.Callable} Java {@link Class interfaces}.
 *
 * @author John Blum
 * @param  {@link Class type} of the execution's {@link Object return value}.
 * @see java.lang.FunctionalInterface
 * @see java.lang.Runnable
 * @see java.util.concurrent.Callable
 * @since 1.0.0
 */
@FunctionalInterface
public interface Executable extends Callable, Runnable {

  /**
   * Indicates whether {@literal this} {@link Object} is running.
   *
   * @return a boolean value indicating whether {@literal this} {@link Object} is running.
   * @throws IllegalStateException if the {@link Object Object's} runnable state cannot be determined.
   */
  default boolean isRunning() {
    throw new IllegalStateException("The runnable state of this object cannot be determined");
  }

  /**
   * Callback method used to execute the intended function encapsulating the logic of the execution.
   *
   * @param args optional array of {@link Object arguments} passed to the execution to perform its function.
   * @return the result of the execution.
   */
  T execute(Object... args);

  /**
   * Computes a result or throws an {@link Exception} if the result could not be computed.
   *
   * @return the computed result.
   * @see #execute(Object...)
   */
  @Override
  default T call() {
    return execute();
  }

  /**
   * Runs this execution to compute a result.
   *
   * @see #execute(Object...)
   */
  @Override
  default void run() {
    execute();
  }
}